diff --git a/Docs/source/radiation.rst b/Docs/source/radiation.rst
index 6587219d74..3bc033a45c 100644
--- a/Docs/source/radiation.rst
+++ b/Docs/source/radiation.rst
@@ -126,7 +126,7 @@ frequency, and :math:`m`, :math:`n` and :math:`p` are constants. For the gray so
 
 ::
 
-    Opacity_dir := rad_power_law
+    OPACITY_DIR := rad_power_law
 
 in your GNUmakefile. See § \ `3.3.1 <#sec:opacpars>`__ for instructions on how
 to configure the parameters used for this opacity setup. If you would prefer a different
diff --git a/Exec/radiation_tests/Rad2Tshock/GNUmakefile b/Exec/radiation_tests/Rad2Tshock/GNUmakefile
index fbaac6067e..d307b537ca 100644
--- a/Exec/radiation_tests/Rad2Tshock/GNUmakefile
+++ b/Exec/radiation_tests/Rad2Tshock/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := gamma_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/radiation_tests/RadBlastWave/GNUmakefile b/Exec/radiation_tests/RadBlastWave/GNUmakefile
index 2bf3943d68..47fc9234fe 100644
--- a/Exec/radiation_tests/RadBlastWave/GNUmakefile
+++ b/Exec/radiation_tests/RadBlastWave/GNUmakefile
@@ -15,7 +15,7 @@ EOS_DIR     := gamma_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/radiation_tests/RadBreakout/GNUmakefile b/Exec/radiation_tests/RadBreakout/GNUmakefile
index 8307c6e975..d2622d680a 100644
--- a/Exec/radiation_tests/RadBreakout/GNUmakefile
+++ b/Exec/radiation_tests/RadBreakout/GNUmakefile
@@ -18,7 +18,7 @@ CASTRO_HOME ?= ../../..
 EOS_DIR     = breakout
 NETWORK_DIR := general_null
 NETWORK_INPUTS = breakout.net
-Opacity_dir = breakout
+OPACITY_DIR = breakout
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/radiation_tests/RadFront/GNUmakefile b/Exec/radiation_tests/RadFront/GNUmakefile
index 39d31d11cf..9d232781ba 100644
--- a/Exec/radiation_tests/RadFront/GNUmakefile
+++ b/Exec/radiation_tests/RadFront/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := gamma_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/radiation_tests/RadShestakovBolstad/GNUmakefile b/Exec/radiation_tests/RadShestakovBolstad/GNUmakefile
index 12d08ee8ea..ac2b5876c0 100644
--- a/Exec/radiation_tests/RadShestakovBolstad/GNUmakefile
+++ b/Exec/radiation_tests/RadShestakovBolstad/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := rad_power_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 # number of radiation groups -  this needs to correspond to radiation.nGroups in
 # the inputs file
diff --git a/Exec/radiation_tests/RadSourceTest/GNUmakefile b/Exec/radiation_tests/RadSourceTest/GNUmakefile
index 19d094f067..e55278b5cd 100644
--- a/Exec/radiation_tests/RadSourceTest/GNUmakefile
+++ b/Exec/radiation_tests/RadSourceTest/GNUmakefile
@@ -20,7 +20,7 @@ EOS_DIR     := rad_power_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 # use radiation interpbndry
 RAD_INTERP = TRUE
diff --git a/Exec/radiation_tests/RadSphere/GNUmakefile b/Exec/radiation_tests/RadSphere/GNUmakefile
index f057ad3ecf..e61be921c0 100644
--- a/Exec/radiation_tests/RadSphere/GNUmakefile
+++ b/Exec/radiation_tests/RadSphere/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := rad_power_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 # number of radiation groups -  this needs to correspond to radiation.nGroups in
 # the inputs file
diff --git a/Exec/radiation_tests/RadSuOlson/GNUmakefile b/Exec/radiation_tests/RadSuOlson/GNUmakefile
index 43c503b9c5..993717dbef 100644
--- a/Exec/radiation_tests/RadSuOlson/GNUmakefile
+++ b/Exec/radiation_tests/RadSuOlson/GNUmakefile
@@ -16,7 +16,7 @@ EOS_DIR     := rad_power_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/radiation_tests/RadSuOlsonMG/GNUmakefile b/Exec/radiation_tests/RadSuOlsonMG/GNUmakefile
index 84bb1ad7bd..de11e671e4 100644
--- a/Exec/radiation_tests/RadSuOlsonMG/GNUmakefile
+++ b/Exec/radiation_tests/RadSuOlsonMG/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := rad_power_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 NGROUPS := 2
 
diff --git a/Exec/radiation_tests/RadThermalWave/GNUmakefile b/Exec/radiation_tests/RadThermalWave/GNUmakefile
index 39d31d11cf..9d232781ba 100644
--- a/Exec/radiation_tests/RadThermalWave/GNUmakefile
+++ b/Exec/radiation_tests/RadThermalWave/GNUmakefile
@@ -17,7 +17,7 @@ EOS_DIR     := gamma_law
 NETWORK_DIR := general_null
 NETWORK_INPUTS := gammalaw.net
 
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/science/bwp-rad/GNUmakefile b/Exec/science/bwp-rad/GNUmakefile
index a97474626d..eeec42e093 100644
--- a/Exec/science/bwp-rad/GNUmakefile
+++ b/Exec/science/bwp-rad/GNUmakefile
@@ -29,7 +29,7 @@ NETWORK_DIR := general_null
 NETWORK_INPUTS := H_He.net
 
 # power-law opacity
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./
 
diff --git a/Exec/science/planet/GNUmakefile b/Exec/science/planet/GNUmakefile
index d61a5223be..769260a58e 100644
--- a/Exec/science/planet/GNUmakefile
+++ b/Exec/science/planet/GNUmakefile
@@ -33,7 +33,7 @@ NETWORK_DIR := general_null
 NETWORK_INPUTS := ./taeho.net
 
 # power-law opacity
-Opacity_dir := rad_power_law
+OPACITY_DIR := rad_power_law
 
 PROBLEM_DIR ?= ./